/*
** $Id: llex.c,v 2.96.1.1 2017/04/19 17:20:42 roberto Exp $
** Lexical Analyzer
** See Copyright Notice in lua.h
*/

#define llex_c
#define LUA_CORE

#include "lprefix.h"

#include <locale.h>
#include <string.h>

#include "lua.h"

#include "lctype.h"
#include "ldebug.h"
#include "ldo.h"
#include "lgc.h"
#include "llex.h"
#include "lobject.h"
#include "lparser.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
#include "lzio.h"

#define next(ls) (ls->current = zgetc(ls->z))

#define currIsNewline(ls) (ls->current == '\n' || ls->current == '\r')

// clang-format off
/* ORDER RESERVED */
static const char *const luaX_tokens [] = {
    "and", "break", "do", "else", "elseif",
    "end", "false", "for", "function", "goto", "if",
    "in", "local", "nil", "not", "or", "repeat",
    "return", "then", "true", "until", "while",
    "//", "..", "...", "==", ">=", "<=", "~=",
    "<<", ">>", "::", "<eof>",
    "<number>", "<integer>", "<name>", "<string>"
};
// clang-format on

#define save_and_next(ls) (save(ls, ls->current), next(ls))

static l_noret lexerror(LexState* ls, const char* msg, int token);

static void save(LexState* ls, int c) {
  Mbuffer* b = ls->buff;
  if (luaZ_bufflen(b) + 1 > luaZ_sizebuffer(b)) {
    size_t newsize;
    if (luaZ_sizebuffer(b) >= MAX_SIZE / 2)
      lexerror(ls, "lexical element too long", 0);
    newsize = luaZ_sizebuffer(b) * 2;
    luaZ_resizebuffer(ls->L, b, newsize);
  }
  b->buffer[luaZ_bufflen(b)++] = cast(char, c);
}

void luaX_init(lua_State* L) {
  int i;
  TString* e = luaS_newliteral(L, LUA_ENV); /* create env name */
  luaC_fix(L, obj2gco(e)); /* never collect this name */
  for (i = 0; i < NUM_RESERVED; i++) {
    TString* ts = luaS_new(L, luaX_tokens[i]);
    luaC_fix(L, obj2gco(ts)); /* reserved words are never collected */
    ts->extra = cast_byte(i + 1); /* reserved word */
  }
}

const char* luaX_token2str(LexState* ls, int token) {
  if (token < FIRST_RESERVED) { /* single-byte symbols? */
    lua_assert(token == cast_uchar(token));
    return luaO_pushfstring(ls->L, "'%c'", token);
  } else {
    const char* s = luaX_tokens[token - FIRST_RESERVED];
    if (token < TK_EOS) /* fixed format (symbols and reserved words)? */
      return luaO_pushfstring(ls->L, "'%s'", s);
    else /* names, strings, and numerals */
      return s;
  }
}

static const char* txtToken(LexState* ls, int token) {
  switch (token) {
    case TK_NAME:
    case TK_STRING:
    case TK_FLT:
    case TK_INT:
      save(ls, '\0');
      return luaO_pushfstring(ls->L, "'%s'", luaZ_buffer(ls->buff));
    default:
      return luaX_token2str(ls, token);
  }
}

static l_noret lexerror(LexState* ls, const char* msg, int token) {
  msg = luaG_addinfo(ls->L, msg, ls->source, ls->linenumber);
  if (token)
    luaO_pushfstring(ls->L, "%s near %s", msg, txtToken(ls, token));
  luaD_throw(ls->L, LUA_ERRSYNTAX);
}

l_noret luaX_syntaxerror(LexState* ls, const char* msg) {
  lexerror(ls, msg, ls->t.token);
}

/*
** creates a new string and anchors it in scanner's table so that
** it will not be collected until the end of the compilation
** (by that time it should be anchored somewhere)
*/
// key = &(G(L)->strt.hash[str])
// ls->h[key] = true;
// return key
TString* luaX_newstring(LexState* ls, const char* str, size_t l) {
  lua_State* L = ls->L;
  TValue* o; /* entry for 'str' */
  TString* ts = luaS_newlstr(L, str, l); /* create new string */
  setsvalue2s(L, L->top++, ts); /* temporarily anchor it in stack */
  o = luaH_set(L, ls->h, L->top - 1);
  if (ttisnil(o)) { /* not in use yet? */
    /* boolean value does not need GC barrier;
       table has no metatable, so it does not need to invalidate cache */
    setbvalue(o, 1); /* t[string] = true */
    luaC_checkGC(L);
  } else { /* string already present */
    // str may be a long string, not in global string table
    ts = tsvalue(keyfromval(o)); /* re-use value previously stored */
  }
  L->top--; /* remove string from stack */
  return ts;
}

/*
** increment line number and skips newline sequence (any of
** \n, \r, \n\r, or \r\n)
*/
static void inclinenumber(LexState* ls) {
  int old = ls->current;
  lua_assert(currIsNewline(ls));
  next(ls); /* skip '\n' or '\r' */
  if (currIsNewline(ls) && ls->current != old)
    next(ls); /* skip '\n\r' or '\r\n' */
  if (++ls->linenumber >= MAX_INT)
    lexerror(ls, "chunk has too many lines", 0);
}

void luaX_setinput(lua_State* L, LexState* ls, ZIO* z, TString* source, int firstchar) {
  ls->t.token = 0;
  ls->L = L;
  ls->current = firstchar;
  ls->lookahead.token = TK_EOS; /* no look-ahead token */
  ls->z = z;
  ls->fs = NULL;
  ls->linenumber = 1;
  ls->lastline = 1;
  ls->source = source;
  ls->envn = luaS_newliteral(L, LUA_ENV); /* get env name */
  luaZ_resizebuffer(ls->L, ls->buff, LUA_MINBUFFER); /* initialize buffer */
}

/*
** =======================================================
** LEXICAL ANALYZER
** =======================================================
*/

// check current char, if true, get next char
static int check_next1(LexState* ls, int c) {
  if (ls->current == c) {
    next(ls);
    return 1;
  } else
    return 0;
}

/*
** Check whether current char is in set 'set' (with two chars) and
** saves it
*/
static int check_next2(LexState* ls, const char* set) {
  lua_assert(set[2] == '\0');
  if (ls->current == set[0] || ls->current == set[1]) {
    save_and_next(ls);
    return 1;
  } else
    return 0;
}

/* LUA_NUMBER */
/*
** this function is quite liberal in what it accepts, as 'luaO_str2num'
** will reject ill-formed numerals.
*/
static int read_numeral(LexState* ls, SemInfo* seminfo) {
  TValue obj;
  const char* expo = "Ee";
  int first = ls->current;
  lua_assert(lisdigit(ls->current));
  save_and_next(ls);
  if (first == '0') {
    if (check_next2(ls, "xX")) { /* hexadecimal? */
      expo = "Pp";
    } else if (check_next2(ls, "oO")) { /* octal? */
    } else if (check_next2(ls, "bB")) { /* binary? */
    }
  }
  for (;;) {
    if (check_next2(ls, expo)) /* exponent part? */
      check_next2(ls, "-+"); /* optional exponent sign */
    if (lisxdigit(ls->current))
      save_and_next(ls);
    else if (ls->current == '.')
      save_and_next(ls);
    else
      break;
  }
  save(ls, '\0');
  if (luaO_str2num(luaZ_buffer(ls->buff), &obj) == 0) /* format error? */
    lexerror(ls, "malformed number", TK_FLT);
  if (ttisinteger(&obj)) {
    seminfo->i = ivalue(&obj);
    return TK_INT;
  } else {
    lua_assert(ttisfloat(&obj));
    seminfo->r = fltvalue(&obj);
    return TK_FLT;
  }
}

/*
** skip a sequence '[=*[' or ']=*]'; if sequence is well formed, return
** its number of '='s; otherwise, return a negative number (-1 iff there
** are no '='s after initial bracket)
*/
static int skip_sep(LexState* ls) {
  int count = 0;
  int s = ls->current;
  lua_assert(s == '[' || s == ']');
  save_and_next(ls);
  while (ls->current == '=') {
    save_and_next(ls);
    count++;
  }
  return (ls->current == s) ? count : (-count) - 1;
}

// read long string, string define or long comment
// if seminfo == NULL, it read for comment, else, for string
// [<-- sep -->[here are string with '\n']<-- sep -->]
static void read_long_string(LexState* ls, SemInfo* seminfo, int sep) {
  int line = ls->linenumber; /* initial line (for error message) */
  save_and_next(ls); /* skip 2nd '[' */
  if (currIsNewline(ls)) /* string starts with a newline? */
    inclinenumber(ls); /* skip it */
  for (;;) {
    switch (ls->current) {
      case EOZ: { /* error */
        const char* what = (seminfo ? "string" : "comment");
        const char* msg = luaO_pushfstring(ls->L, "unfinished long %s (starting at line %d)", what, line);
        lexerror(ls, msg, TK_EOS);
        break; /* to avoid warnings */
      }
      case ']': {
        if (skip_sep(ls) == sep) {
          save_and_next(ls); /* skip 2nd ']' */
          goto endloop;
        }
        break;
      }
      case '\n':
      case '\r': {
        save(ls, '\n');
        inclinenumber(ls);
        if (!seminfo)
          luaZ_resetbuffer(ls->buff); /* avoid wasting space */
        break;
      }
      default: {
        if (seminfo)
          save_and_next(ls);
        else
          next(ls);
      }
    }
  }
endloop:
  if (seminfo)
    seminfo->ts = luaX_newstring(ls, luaZ_buffer(ls->buff) + (2 + sep), luaZ_bufflen(ls->buff) - 2 * (2 + sep));
}

static void esccheck(LexState* ls, int c, const char* msg) {
  if (!c) {
    if (ls->current != EOZ)
      save_and_next(ls); /* add current to buffer for error message */
    lexerror(ls, msg, TK_STRING);
  }
}

static int gethexa(LexState* ls) {
  save_and_next(ls);
  esccheck(ls, lisxdigit(ls->current), "hexadecimal digit expected");
  return luaO_hexavalue(ls->current);
}

static int readhexaesc(LexState* ls) {
  int r = gethexa(ls);
  r = (r << 4) + gethexa(ls);
  luaZ_buffremove(ls->buff, 2); /* remove saved chars from buffer */
  return r;
}

static unsigned long readutf8esc(LexState* ls) {
  unsigned long r;
  int i = 4; /* chars to be removed: '\', 'u', '{', and first digit */
  save_and_next(ls); /* skip 'u' */
  esccheck(ls, ls->current == '{', "missing '{'");
  r = gethexa(ls); /* must have at least one digit */
  while (((void)(save_and_next(ls)), lisxdigit(ls->current))) {
    i++;
    r = (r << 4) + luaO_hexavalue(ls->current);
    esccheck(ls, r <= 0x10FFFF, "UTF-8 value too large");
  }
  esccheck(ls, ls->current == '}', "missing '}'");
  next(ls); /* skip '}' */
  luaZ_buffremove(ls->buff, i); /* remove saved chars from buffer */
  return r;
}

static void utf8esc(LexState* ls) {
  char buff[UTF8BUFFSZ];
  int n = luaO_utf8esc(buff, readutf8esc(ls));
  for (; n > 0; n--) /* add 'buff' to string */
    save(ls, buff[UTF8BUFFSZ - n]);
}

static int readdecesc(LexState* ls) {
  int i;
  int r = 0; /* result accumulator */
  for (i = 0; i < 3 && lisdigit(ls->current); i++) { /* read up to 3 digits */
    r = 10 * r + ls->current - '0';
    save_and_next(ls);
  }
  esccheck(ls, r <= UCHAR_MAX, "decimal escape too large");
  luaZ_buffremove(ls->buff, i); /* remove read digits from buffer */
  return r;
}

// del: delimiter, " or '
// seminfo: for store the string, (TString type)
static void read_string(LexState* ls, int del, SemInfo* seminfo) {
  save_and_next(ls); /* keep delimiter (for error messages) */
  while (ls->current != del) {
    switch (ls->current) {
      case EOZ:
        lexerror(ls, "unfinished string", TK_EOS);
        break; /* to avoid warnings */
      case '\n':
      case '\r':
        lexerror(ls, "unfinished string", TK_STRING);
        break; /* to avoid warnings */
      case '\\': { /* escape sequences */
        int c; /* final character to be saved */
        save_and_next(ls); /* keep '\\' for error messages */
        switch (ls->current) {
          case 'a':
            c = '\a';
            goto read_save;
          case 'b':
            c = '\b';
            goto read_save;
          case 'f':
            c = '\f';
            goto read_save;
          case 'n':
            c = '\n';
            goto read_save;
          case 'r':
            c = '\r';
            goto read_save;
          case 't':
            c = '\t';
            goto read_save;
          case 'v':
            c = '\v';
            goto read_save;
          case 'x':
            c = readhexaesc(ls);
            goto read_save;
          case 'u':
            utf8esc(ls);
            goto no_save;
          case '\n':
          case '\r':
            inclinenumber(ls);
            c = '\n';
            goto only_save;
          case '\\':
          case '\"':
          case '\'':
            c = ls->current;
            goto read_save;
          case EOZ:
            goto no_save; /* will raise an error next loop */
          case 'z': { /* zap following span of spaces */
            luaZ_buffremove(ls->buff, 1); /* remove '\\' */
            next(ls); /* skip the 'z' */
            while (lisspace(ls->current)) {
              if (currIsNewline(ls))
                inclinenumber(ls);
              else
                next(ls);
            }
            goto no_save;
          }
          default: {
            esccheck(ls, lisdigit(ls->current), "invalid escape sequence");
            c = readdecesc(ls); /* digital escape '\ddd' */
            goto only_save;
          }
        }
      read_save:
        next(ls);
        /* go through */
      only_save:
        luaZ_buffremove(ls->buff, 1); /* remove '\\' */
        save(ls, c);
        /* go through */
      no_save:
        break;
      }
      default:
        save_and_next(ls);
    }
  }
  save_and_next(ls); /* skip delimiter */
  seminfo->ts = luaX_newstring(ls, luaZ_buffer(ls->buff) + 1, luaZ_bufflen(ls->buff) - 2);
}

// get the next token, return the token
// if next token is double, int, or string, store it's value(or ptr) in seminfo
static int llex(LexState* ls, SemInfo* seminfo) {
  luaZ_resetbuffer(ls->buff);
  for (;;) {
    switch (ls->current) {
      case '\n':
      case '\r': { /* line breaks */
        inclinenumber(ls);
        break;
      }
      case ' ':
      case '\f':
      case '\t':
      case '\v': { /* spaces */
        next(ls);
        break;
      }
      case '-': { /* '-' or '--' (comment) */
        next(ls);
        if (ls->current != '-')
          return '-';
        /* else is a comment */
        next(ls);
        if (ls->current == '[') { /* long comment? */
          int sep = skip_sep(ls);
          luaZ_resetbuffer(ls->buff); /* 'skip_sep' may dirty the buffer */
          if (sep >= 0) {
            read_long_string(ls, NULL, sep); /* skip long comment */
            luaZ_resetbuffer(ls->buff); /* previous call may dirty the buff. */
            break;
          }
        }
        /* else short comment */
        while (!currIsNewline(ls) && ls->current != EOZ)
          next(ls); /* skip until end of line (or end of file) */
        break;
      }
      case '[': { /* long string or simply '[' */
        int sep = skip_sep(ls);
        if (sep >= 0) {
          read_long_string(ls, seminfo, sep);
          return TK_STRING;
        } else if (sep != -1) /* '[=...' missing second bracket */
          lexerror(ls, "invalid long string delimiter", TK_STRING);
        return '[';
      }
      case '=': {
        next(ls);
        if (check_next1(ls, '='))
          return TK_EQ;
        else
          return '='; // come to here, check_next1 will not take the next char
      }
      case '<': {
        next(ls);
        if (check_next1(ls, '='))
          return TK_LE;
        else if (check_next1(ls, '<'))
          return TK_SHL;
        else
          return '<';
      }
      case '>': {
        next(ls);
        if (check_next1(ls, '='))
          return TK_GE;
        else if (check_next1(ls, '>'))
          return TK_SHR;
        else
          return '>';
      }
      case '/': {
        next(ls);
        if (check_next1(ls, '/'))
          return TK_IDIV;
        else
          return '/';
      }
      case '~': {
        next(ls);
        if (check_next1(ls, '='))
          return TK_NE;
        else
          return '~';
      }
      case ':': {
        next(ls);
        if (check_next1(ls, ':'))
          return TK_DBCOLON;
        else
          return ':';
      }
      case '"':
      case '\'': { /* short literal strings */
        read_string(ls, ls->current, seminfo);
        return TK_STRING;
      }
      case '.': { /* '.', '..', '...', or number */
        save_and_next(ls);
        if (check_next1(ls, '.')) {
          if (check_next1(ls, '.'))
            return TK_DOTS; /* '...' */
          else
            return TK_CONCAT; /* '..' */
        } else if (!lisdigit(ls->current))
          return '.';
        else
          return read_numeral(ls, seminfo);
      }
      case '0':
      case '1':
      case '2':
      case '3':
      case '4':
      case '5':
      case '6':
      case '7':
      case '8':
      case '9': {
        return read_numeral(ls, seminfo);
      }
      case EOZ: {
        return TK_EOS;
      }
      default: {
        if (lislalpha(ls->current)) { /* identifier or reserved word? */
          TString* ts;
          do {
            save_and_next(ls);
          } while (lislalnum(ls->current));
          ts = luaX_newstring(ls, luaZ_buffer(ls->buff), luaZ_bufflen(ls->buff));
          seminfo->ts = ts;
          if (isreserved(ts)) /* reserved word? */
            return ts->extra - 1 + FIRST_RESERVED;
          else {
            return TK_NAME;
          }
        } else { /* single-char tokens (+ - / ...) */
          int c = ls->current;
          next(ls);
          return c;
        }
      }
    }
  }
}

// get the next token, store pointer in ls->t
void luaX_next(LexState* ls) {
  ls->lastline = ls->linenumber;
  if (ls->lookahead.token != TK_EOS) { /* is there a look-ahead token? */
    ls->t = ls->lookahead; /* use this one */
    ls->lookahead.token = TK_EOS; /* and discharge it */
  } else
    ls->t.token = llex(ls, &ls->t.seminfo); /* read next token */
}

// look what's the next token, but not take it, only support look 1 token
int luaX_lookahead(LexState* ls) {
  lua_assert(ls->lookahead.token == TK_EOS);
  ls->lookahead.token = llex(ls, &ls->lookahead.seminfo);
  return ls->lookahead.token;
}
